A much vaunted and highly publicized search for the remains of Amelia Earhart has apparently turned up little in the way of new evidence to help solve the puzzle of the famous aviator’s ultimate fate. A team of researchers, armed with an array of high-tech gear, spent the past week searching a remote island in the South Pacific, but appear to have come up short in their quest to solve one of the most enduring mysteries of the 20th century.

We first told you about the expedition, which was spurred on by intriguing new evidence, at the beginning of the month. At that time the research team was just setting out for Nikumaroro, the tiny island that some believe may have been the final resting place for Earhart and her navigator Fred Noonan. The duo went missing back in 1937 while attempting to fly around the world, leaving many to ponder their fate for the next 75 years.

This most recent search for their whereabouts cost $2.2 million and employed the use of high-definition underwater cameras and sensitive sonar in an attempt to locate Earhart’s Lockheed Electra aircraft. According to Reuters, those efforts were stymied by equipment failures and steep, rocky terrain just off the coast of Nikumaroro. The coral reefs that surround the atoll feature craggy outcroppings and severe drops, with depths ranging from 110 to 250 feet. Those natural obstructions slowed down the search process and ultimately led the search team to cut short the expedition and return to Hawaii.

The researchers say that the expedition wasn’t for nothing, however, and that they are returning home with hours of video and sonar data to pore over. While they weren’t able to identify the wreckage from what they’ve seen so far, they hope that when they get the opportunity to analyze it later they’ll be able to find some hidden clues. They’ll have to search quickly, however, as a television show about the expedition is set to air on the Discovery Channel on August 19.